Fix race on mojo message pump shutdown.

base/threading/thread_restrictions.h

Index: base/threading/thread_restrictions.h
diff --git a/base/threading/thread_restrictions.h b/base/threading/thread_restrictions.h
index f0d3faf6592b1777b01a2962ba4362b53de2e38d..76374467c9f943a9aa4a8e87d042940629fc00a3 100644
--- a/base/threading/thread_restrictions.h
+++ b/base/threading/thread_restrictions.h
@@ -56,6 +56,11 @@ class InFlightIO;
 namespace gles2 {
 class CommandBufferClientImpl;
 }
+namespace mojo {
+namespace common {
+class MessagePumpMojo;
+}
+}
 namespace net {
 class NetworkChangeNotifierMac;
 namespace internal {
@@ -199,6 +204,7 @@ class BASE_EXPORT ThreadRestrictions {
   friend class PlatformThread;
   friend class android::JavaHandlerThread;
   friend class gles2::CommandBufferClientImpl;
+  friend class mojo::common::MessagePumpMojo;
 
   // END ALLOWED USAGE.
   // BEGIN USAGE THAT NEEDS TO BE FIXED.